Need Help!! No waterflow through drive!
 

My boat fired right up after the long winter but water isn't flowing through the outdrive. I had it in the driveway with the flusher on the outdrive, disconnected the intake hose from the t-stat, started it up and got some flow but definitely not enough. What could it be? The impeller was my first thought but the flow was strong when I winterized the motor last year. How likely is it for a cooler to be blocked? I think there are 3 coolers inline before water gets to the motor, pwr steering, oil, and fuel.:confused: :confused: :confused:

What's worse is that my warranty is up Monday!!

What drive and how many hrs? The rubber impellers take a set in the winter and then the blades break off when you start it up in spring. Make sure you find all the parts. The like to end up in the coolers.

must likely the impeller, is gummed up or full of ****, i would check that first, or try blowing out the lines to see if the is good pressure.

It's a Bravo HP LWP 47hrs. How do I check the impeller without taking the lower off? Would Merc cover this, I still have 2 days left on my warranty?

have to pull apart to check, see by eye if there is damage, they might i would check, or they will say it was a wear factor, or you ran it with no water supply depends on your dealership.

DJM,

The impellor is on the engine, sea pump is low and to the starboard side - As formula 31 pointed out, This is pretty common in the spring, and find all the pieces.

The impellor is not covered by the warranty.

I thought the impeller was in the drive?

the impeller is in the lower unit on alpha drives, on bravo it is in the raw water pump on the engine, follow your water lines from lower unit to pump, its has a supply and return hose on the back of the pump.

hope that was clear, but the supply line draws the water in from lower unit, and return pushes it through engine.

No chit? Is it something a mechanically inclined person can do? I hope it's easier than changing an alpha impeller.

The big headache is getting the pump out of there. You have to get the hoses off (not easy) (write down which hose goes where) and then remove the bracket from the block. Take the pump out bracket and all. Then take lots of pictures so you know how the bracket goes back on the pump and take it apart. You will need new gaskets, end plates and an impeller. If its a newer one I think the end plate where the hoses hook up is part of the body. If the impeller is missing vanes, find them. Sometimes they go right to the oil cooler, another fun thing to get at. I hope you dont have twins, then its a lot more fun (lots of swearing).:)

djm, I had the same problem as you when I fired up my engine a few weeks ago after the winter layup. Problem was that I used one of those winterizing kits that you put the anti-freeze in and let it gravity feed to the muffs on the outdrive. Had good water flow at the time, but all I was doing was burning up the impeller the whole time. Bravos really need a good water supply. Long story short, ended up changing my entire pump housing it had worn so badly. From now on I will drain the entire system and be done with it. You can change the impeller, it's not too bad a job. Andy

If you go to www.mercruiserparts.com you should be able to look up your engine and see a diagram of the raw water pump with the impeller. It will make it easier to understand what everyone is talking about. It is a pretty simple job.

The rebuild kit is about $75 at the above mentioned website. It's not that hard to do. You will probably have to pull the fuel pump off (2 nuts, but it's in a plastic case that pulls off) and push it to the side to get the water pump. I didn't take the bracket off when I did mine. I just took all the nuts holding the pump to the bracket off. I think there about 5. Pull the water lines and out it comes. Oh yeah, you have to take the belt off first..:rolleyes:

Good Luck!

this job is really simple, if you have room to work in your engine compartment, when you put the impeller back in the housing make sure the rotation is correct so when you start up the impeller doesn't have to reverse direction. use some dish soap to lube impeller for start up.

Thanks for all the replies, love this board. I'm confused though, how many water pumps are there? I thought two, one that is bolted on the front of the engine, ran by the serpentine belt, and pushes water through the block and exhaust. The second is the one I burned up I think. It is located on the starboard side really low and has two hoses going to it, it pulls/pushes water from the drive, not sure what drives it though. Both of these pumps have an impeller. Does that sound right?

Posted too soon before. I checked the diagram (Thanks Griff) and found the sea water pump but don't recognize it. Here's a link to a pic of a 502 cooling system. Hose 11 and 12 connect to what they call a sea water pump but looks different than what is driven by a belt. What gives? Is it the same thing minus the pulley.

http://www.mercruiserparts.com/Show_...88%2E2L+MPI%29

that is the seawater pump without the pulley, click on seawater pump and it gives you the break down of it, empeller, pulley, etc.

rod

djm, the "pump" on the front of the block is a water circulator pump. It doesn't do a whole hell of a lot on a marine engine - a lot of people replace them with crossovers to get more HP. The impeller is in the sea water pump.

OK - just so I have this straight. On newer Bravo I's (98 7.4L), there is NO impeller in the outdrive? The impeller is in the sea water pump? I was going to pull my drive to change this. I guess I don't have to???:confused:

The impeller job is not too bad ... I had to do it at the launch ramp one day ... it was either figure out how to change it or back to storage with my tail tucked between my legs. I usually keep a new impeller onboard but I had just given it to a friend a few weeks before. Luckily there is a West Marine within walking distance. It was a learning experience but I got it changed in 1hr 45min. Next time it won't take over an hour. I know you should backflush the system whenever a blade is missing but, a quick impeller R&R can save a boating day. Just think if it happens while out on the water.

G

Thanks everybody. I'm pulling the impeller Thursday and backflushing while I'm in there. Now if I could only find a decent place to install a sea strainer....
Thanks again.

Try WWW.boatfix.com for an inexpensive rebuild kit. Got mine for $45.

most people I know recommend replacing the impellars every 2 years. Wether it needs it or not.
safe insurance.
If you boat in sandy or muddy waters even every year is good practice.
Only 35 bucks for the impellar. Saves from chewing up the housing which is over 200. No need to change the wear plate or outer housing until it gets groved out. 2 for one if you do pre-maintenance.
Mine will be done before spring start up :)